Okay, I'm not sure I understand where you're coming from.
If you mean ECL, that's just a balancing factor for PCs. Let's say you want to play a true werewolf, which is an ECL +3. So, if your party is 4th level, you can be a 1st level True Lycanthrope. This is a balance issue, to ensure you don't outshine everyone because they're the same level as you, but you have all your cool werewolf powers.
If you mean the HD thing, then here, let me explain it how it was explained to me. You take the highest number of HPs and HD.
Let's say a 1st level wizard is infected by a werewolf. Now, the wizard has 1 hit die, a d4. Now, the werewolf has 2 hit die, 2d8.
In this case, you roll the 2d8, and if it's grater then the wizard's current hit points, the 2d8 number you rolled is his current hit points, in human, hybrid and animal form.
Also, he is treated as a 2 HD creature, for things like spells that are ment for Hit dice.
If you mean ECL, that's just a balancing factor for PCs. Let's say you want to play a true werewolf, which is an ECL +3. So, if your party is 4th level, you can be a 1st level True Lycanthrope. This is a balance issue, to ensure you don't outshine everyone because they're the same level as you, but you have all your cool werewolf powers.
If you mean the HD thing, then here, let me explain it how it was explained to me. You take the highest number of HPs and HD.
Let's say a 1st level wizard is infected by a werewolf. Now, the wizard has 1 hit die, a d4. Now, the werewolf has 2 hit die, 2d8.
In this case, you roll the 2d8, and if it's grater then the wizard's current hit points, the 2d8 number you rolled is his current hit points, in human, hybrid and animal form.
Also, he is treated as a 2 HD creature, for things like spells that are ment for Hit dice.
